Among numerous kinds of power devices, DMOS (double-diffused metal oxide semiconductor FET) is characterized by high switching speed, high conversion efficiency in the low voltage region, and compatibility between high breakdown voltage and low on-resistance. With regard to specific applications, DMOS is widely used as a switching element in a motor driver, power supply and the like, and as an analog output element in an audio amplifier.
Techniques for incorporating DMOS having a plurality of breakdown voltage levels on one chip have also been developed. Thus, a DMOS having an appropriate breakdown voltage can be used in accordance with the purpose of the circuit. This can optimize the chip size. However, also in this case, to ensure the breakdown voltage of the entire chip, the punch through voltage to the substrate is preferably set to a certain value or more among a plurality of kinds of DMOS having different breakdown voltage levels.